unit 5 D.B. math

1 .Find the pH of a substance of your choice that is alkaline (basic Using this pH , show how to find the hydrogen ion concentration , [H ] , of the substance using the formula . Discuss the meaning of pH and [H ] , the pH scale and why your chosen substance is alkaline . Use scientific notation or enough decimal places so that your answer has at least 3 place values . For example , either use 3 .44 10-9 or 0

The formula for pH

pH -log10[H ] where [H ] is the hydrogen ion concentration of

a substance

By logarithmic transformation we get

10^pH - [H ]

By additive property we get

[H ] -10^pH

Suppose we have lime which has a pH of 12 .4 then

[H ] - (10^12 .4

[H ] - (2 .5119 10^12

[H ] -2 .5119 10^12

Lime , with a pH of 12 , has a hydrogen ion concentration of -2 .5119 10^12 mol /liter . The pH is a number in which one can determine the alkalinity (basic ) or acidity of a substance . The pH scale range is from 1 to 14 where 1 is the most acidic and 14 the most basic (Biology-online . [H ] on the other hand is the amount of hydrogen molecule that is present in a substance . The [H ] is used to approximate the pH of a substance

2 . Suppose that the number of new homes built , H , in a city over a period of time , t , is graphed on a rectangular coordinate system where time is on the horizontal axis . Suppose that the number of homes built can be modeled by an exponential function , H

at , where

is the number of new homes built in the first year recorded . If you were a homebuilder looking for work , would you prefer that the value of a to be between 0 and 1 or larger than 1 ? Explain your reasoning . Be sure to reference your sources using APA style

The graph of the exponential function H

at is increasing and the value of the function will never be zero . If I were a homebuilder I will choose my a to be greater than 1 so that the demand for houses to be built will be bigger each and every year so that I will not lose my job

Say there are 10 homes on the first year

Support equations : if I will use a to be between zero and 1 , say 1 , then

H 10^ (1 2 1000 new homes

But if I will choose my a to be greater than 1 , say 2 , then

H 10^ (2 2 10000 new homes

Comparing the two equations we can see the big difference in the number of homes

My a should be greater than 1

Reference

Biology-Online . Ph . 11 June 2007 . Biology-Online .org . Retrieved September 23 , 2008 from

Unit 5 Discussion Board PAGE 2

Unit 5 Discussion Board PAGE 1...